enter a word prefix and press TAB – and the prefix will be
expanded from all the words on the current channel on everything
that was said by yourself or by others – provided that its
length is at least $backlog_complete_min_length and at most
$backlog_complete_max_length long, and consists only of letters
in $backlog_complete_word_chars. word case does not matter.
Using irssi? Install it by copying it to ~/.irssi/scripts/backlog_completion.pl and running ‘/script load backlog_completion.pl’ inside irssi then. Enjoy pressing <tab>.